Method and aparatus for automated biopsy and collection of soft tissue

ABSTRACT

A bipolar electrosurgical instrument is described which may be used for heating the inner lining of a lumen or cavity within a patient. In particular, the present invention is directed to an electrosurgical instrument including a flexible elongated tube having a proximal and a distal end, a first balloon electrode attached to the distal end of the flexible elongated tube. The first balloon electrode includes a first expandable sleeve formed from an electrically insulating material and a first electrically conductive fluid in the expandable sleeve. A first electrode is positioned in electrical contact with the first electrically conductive fluid. A return balloon electrode is spaced proximally from the first balloon electrode, wherein the return balloon electrode includes a second expandable formed from an electrically insulating material and a second electrically conductive fluid disposed within the second expandable sleeve. A return electrode is positioned in electrical contact with the second electrically conductive fluid.

FIELD OF THE INVENTION

[0001] The present invention relates, in general, to an electrosurgicalinstrument for heating the inner lining of a lumen or cavity within apatient and, more particularly, a bipolar RF balloon electrosurgicalinstrument for the treatment of Barrett's Esophagus.

BACKGROUND OF THE INVENTION

[0002] The human body has a number of internal body lumens or cavitieslocated within, many of which have an inner lining or layer. These innerlinings can be susceptible to disease. In some cases, surgicalintervention can be required to remove the inner lining in order toprevent the spread of a disease to otherwise healthy tissue locatednearby.

[0003] Barrett's Esophagus is a disease wherein the healthy innermucosal lining (stratified squamous epithelium) of the esophagus isreplaced with diseased tissue (abnormal columnar epithelium). Barrett'sEsophagus results from chronic exposure of the mucosal lining toirritating gastric secretions. In gastroesophageal reflux disease (GERD)the lower esophageal sphincter fails to close properly and gastricsecretions or reflux migrate upwards from the stomach to the lowerportions of the esophagus exposing the esophagus to gastric secretionswhich may cause Barrett's Esophagus. The occasional exposure of theesophagus to gastric secretions is not harmful, but chronic exposure canirritate the mucosal lining and create abnormal mucosal cells. In acertain percentage of the population, the abnormal cells can be aprecursor to the development of esophageal cancer. Esophageal cancer isone of the most lethal of all cancers and initial diagnosis is difficultwithout a visual inspection of the esophagus.

[0004] Treatment of GERD ranges from the administration of anti acids inmild cases to surgery such as a Nissen fundoplication. The Nissenfundoplication requires surgical opening of the patient, and thewrapping and suturing of a portion of the stomach around the lowerportion of the esophagus to create an esophageal sphincter. Due to age,health, severity of GERD, and other factors, not all patients arecandidates for surgery such as the Nissen fundoplication. As aconsequence, the medical profession has tended to treat GERD symptomsrather than eradicating the root cause.

[0005] When a patient is diagnosed as having Barrett's Esophagus, thetraditional treatment has been monitoring of the condition and, as alast resort, surgical removal of the diseased inner mucosal layer. Dueto the location of the esophagus within the thoracic cavity and its'close proximity to the lungs, heart and other vascular structures, opensurgery is a major undertaking.

[0006] Medical experimentation has shown that heating or cooking theinner lining of an organ, body structure, or lumen results in thesloughing off of the heated inner lining and (in many cases) eliminationof the disease condition. The mucosal inner lining regrows as healthytissue if the underlying tissue is not diseased or damaged. There are avariety of methods of heating or cooking the inner lining such as theapplication of laser light, plasma, resistance heating, the applicationof warm fluids or warm objects, photodynamic therapy, microwaves, or theapplication of Radio Frequency (RF) energy to the tissue. An overview ofseveral of these methods of treatment can be found in an article byRichard E. Sampliner entitled “New Treatments for Barrett's Esophagus”which was published in Seminars in Gastrointestinal Disease, Vol 8. No.2 (April), 1997: pp 68-74.

[0007] In the above list of possible methods of heating tissue fortreatment of Barrett's Esophagus, the application of RF energy hasspecial interest, and in particular, the use of a RF balloon surgicalinstrument to deliver the energy to a body lumen or cavity. As describedin U.S. Pat. No. 2,032,859 by F. C. Wappler, a RF balloon is especiallyeffective for superficial desiccation or heating of tissue, such as theinner layer or lining of a lumen or cavity. The RF balloon described byF.C. Wappler was of monopolar design. Monopolar RF balloon devices use afirst pole ground pad placed upon the exterior of the patient and asecond (mono)pole balloon electrode placed within the patient and incontact with the diseased tissue. The second pole balloon electrode hasan expandable made from a dielectric or non-conducting material, isfilled with a conductive fluid, and has an electrode adjacent to theballoon and in contact with the conductive fluid. When applying RFenergy to the human body with a bipolar electrosurgical device, it isimportant to establish firm contact with the tissue to reduce thepossibility of burns. The balloon electrode, when inflated within alumen or cavity within the body, expands outwards to adjust to theirregular contours of the lumen or cavity and firmly contacts thediseased tissue. The use of a non-conducting balloon as the tissuecontact surface does not allow the direct coupling of RF energy to thetissue but rather forms a capacitive coupling with the tissue. Thecapacitive coupling of RF energy results in a gentle heating of thetissue in contact with the balloon electrode.

[0008] Whereas the Wappler bipolar RF balloon was indeed a breakthrough,the invention required the insertion of a limp or non-rigid balloon intoa body lumen or cavity. Insertion of a non-rigid balloon into a muscularbody cavity or lumen was difficult at best. Geddes et al. in U.S. Pat.No. 4,979,948 addressed this issue by describing a monopolar RF Balloonhaving a rigid elongated member extending longitudinally into theballoon. The elongated member is attached to the proximal base of theballoon and extends freely into the remainder of the balloon. Thiselongated member provides the necessary rigidity to support theun-inflated balloon during insertion into a body lumen or cavity.Additionally, the second pole electrode of this invention is placedaround the elongated member extending within the balloon for contactwith the electrolytic or conducting fluid used to expand the balloon.

[0009] The Geddes et al. monopolar invention was indeed easier to insertinto the patient, but the attachment of the base of the balloon to theelongated member left the proximal end of the balloon free to moverelative to the elongated member. When the instrument is placed into abody lumen or cavity and the balloon is inflated, it is possible to biasthe distal end of the balloon relative to the distal end of thesupporting member. This moves the second pole electrode off centerrelative to the balloon and may result in uneven heating of the tissueclosest to the second pole electrode.

[0010] What was needed was an RF balloon instrument that reduces thepossibilities of uneven tissue heating or balloon burn through. U.S.Pat. No. 4,7676,258 was issued to Kiyoshi Inokuchi et al. for a flexiblemonopolar balloon that attaches both proximally and distally to thedistal end of a flexible shaft of the instrument. Whereas the Inokuchiet al. monopolar balloon utilized proximal and distal attachment of theballoon to the flexible shaft of the instrument, the monopolar designrequired the use of a second electrode that is placed on the outercircumference of the patient and the use of a constant flow of coolingfluid. An elongated resilient flexible electrode member (made fromconductive material) that extends into an electrosurgical balloon isdescribed in the F. C. Wappler U.S. Pat. No. 2,043,083.

[0011] All RF balloon inventions described above are monopolar andrequire the use of a return pole electrode or pad placed in contact withthe exterior of the patient. U.S. Pat. No. 5,578,008 was issued toShinji Hara for a bipolar balloon catheter wherein both the proximal andthe distal end of the RF balloon is attached to the catheter (rigidsupport member) and has both (bipolar) electrodes located within theballoon. The bipolar RF balloon is fixed relative to both the catheterand reduces the possibilities of uneven heating described above. Thebipolar electrode design heats the cooling liquid within the balloon andthe heated liquid heats the tissue in contact with the balloon.

[0012] It is frequently difficult for a surgeon to access a surgicalsite, particularly when the goal is to access the surgical site withoutcutting or opening the patient. Atraumatic access is typically achievedby admitting the surgical instrument into the patient through a naturalbody orifice, and manipulating or maneuvering the surgical instrument tothe desired location. Since the human body rarely has linear passagewaysor structures, access to a surgical site can require the surgicalinstrument to bend or flex. As the surgeon is manipulating the surgicalinstrument around corners to attain access to the surgical site, caremust be taken to avoid traumatic tissue damage caused by the instrument.Thus, it would be advantageous to design an RF balloon end effector witha means to help guide the end effector around corners and, moreparticularly, to guide the end effector around corners when navigating atorturous lumen or passage. A U.S. Pat. No. 5,558,672 by Edwards et al.teaches a porous monopolar RF balloon that has viewing optics thatextend from the distal end of the balloon.

[0013] It would further be advantageous to provide the surgeon with a RFballoon electrosurgical instrument that can fit down the operatingchannel of an endoscope enabling the surgeon to visually place theballoon electrode at the surgical site. Shinji Hara in U.S. Pat. No.5,578,008 and Jackson et al. in U.S. Pat. No. 4,676,258 describe the useof pulses or bursts to deliver energy from the electrosurgical generatorto the balloon electrode. What is not disclosed in these inventions isthe delivery of pulsed or burst RF electrical energy in a preset patternto produce specific tissue effects.

SUMMARY OF THE INVENTION

[0014] The present invention is directed to a bipolar electrosurgicalinstrument for heating the inner lining of a lumen or cavity within apatient. In particular, the present invention is directed to anelectrosurgical instrument including a flexible elongated tube having aproximal and a distal end, a first balloon electrode attached to thedistal end of the flexible elongated tube. The first balloon electrodeincludes a first expandable sleeve formed from an electricallyinsulating material and a first electrically conductive fluid in theexpandable sleeve. A first electrode is positioned in electrical contactwith the first electrically conductive fluid. A return balloon electrodeis spaced proximally from the first balloon electrode, wherein thereturn balloon electrode includes a second expandable sleeve formed froman electrically insulating material and a second electrically conductivefluid disposed within the second expandable sleeve. A return electrodeis positioned in electrical contact with the second electricallyconductive fluid.

[0015] Further embodiments of the present invention are directed to abipolar electrosurgical instrument having some or all of the followingcharacteristics. The first expandable sleeve is expanded such that aportion of the first expandable sleeve is in contact with a firstportion of the inner lining and a portion of the second expandablesleeve is in contact with a second portion of the inner lining such thatthe second portion of the inner lining is at least twice as large inarea as the first portion of the inner lining. The second expandablesleeve has a length L wherein a proximal end of the first expandablesleeve is positioned a distance of at least 2L from a distal end of thesecond expandable sleeve. The electrically insulating material has alower electrical permeativity than the flexible elongated tube. Abipolar electrosurgical instrument wherein the instrument includes anon-conducting semi-rigid support extending distally within theexpandable sleeve from a distal end of the flexible elongated tube.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The novel features of the invention are set forth withparticularity in the appended claims. The invention itself, however,both as to organization and methods of operation, together with furtherobjects and advantages thereof, may best be understood by reference tothe following description, taken in conjunction with the accompanyingdrawings in which:

[0017]FIG. 1 is an isometric view of a bipolar electrosurgicalinstrument;

[0018]FIG. 2 is an isometric view of a bipolar electrosurgicalinstrument wherein the electrosurgical instrument is attached to anendoscope;

[0019]FIG. 3 is a side view of a locking mechanism locking the bipolarelectrosurgical instrument about a shaft of the endoscope.

[0020]FIG. 4 is a side view, of the balloon electrode illustrated inFIG. 3;

[0021]FIG. 5 is a side view, in cross section, showing the elements ofthe balloon electrode of FIG. 4;

[0022]FIG. 6 is an exploded isometric view of the balloon electrodeillustrated in FIG. 5;

[0023]FIG. 7 is a side view, in cross section, of the balloon electrodeof FIG. 6 wherein the balloon electrode has been expanded;

[0024]FIG. 8 is a side view, in cross section, of an alternateembodiment of the second pole balloon electrode;

[0025]FIG. 9 is a side view, in cross section, of the alternateembodiment of the second pole balloon electrode showing the current flowpatterns;

[0026]FIG. 10 is a side view of the return balloon electrode of thebipolar electrosurgical instrument of FIG. 1;

[0027]FIG. 11 is a side view, in cross section, of the return balloonelectrode of FIG. 1 showing an expandable sleeve in an expanded position(dashed lines) and an unexpanded position (solid lines);

[0028]FIG. 12 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach showing a diseasecondition called Barrett's Esophagus;

[0029]FIG. 13 is a cross sectional view of a patient wherein anendoscope has been inserted into the patient's mouth and esophagus toposition an expanded balloon electrode and a return balloon electrode ofthe bipolar electrosurgical instrument at the surgical site;

[0030]FIG. 14 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach of FIG. 12 showing theplacement of an expanded balloon electrode at the surgical site prior totreatment;

[0031]FIG. 15 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach of FIG. 12 showing theplacement of the balloon electrode and the return balloon electrode ofthe bipolar electrosurgical instrument at the surgical site prior totreatment;

[0032]FIG. 16 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach of FIG. 12 showing themovement of the return balloon electrode of the bipolar electrosurgicalinstrument to a preferred spacing from the balloon electrode at thesurgical site prior to treatment;

[0033]FIG. 17 is a cross sectional view of a flexible return sleeve ofthe bipolar return sleeve of FIG. 16;

[0034]FIG. 18 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach of FIG. 12 showing theimproved visibility that a translucent balloon electrode provides whenvisually positioning the balloon electrode at a preferred position atthe surgical site;

[0035]FIG. 19 is a cross sectional view of the lower portion of theesophagus and the upper portion of the stomach of FIG. 12 showing theimproved visibility that a transparent balloon electrode provides whenvisually positioning the balloon electrode at a preferred position atthe surgical site;

[0036]FIG. 20 is a cross sectional view of a distal end of an alternateembodiment of the bipolar balloon electrode wherein a pair of balloonsare located side by side to the longitudinal axis of the bipolarelectrosurgical instrument;

[0037]FIG. 21 is a side view of an alternate embodiment of the bipolarelectrosurgical instrument having switchable balloons for selectivelumen ablation;

[0038]FIG. 22 is a view of a typical sinusoidal RF waveform produced byan electrosurgical generator for cauterizing tissue;

[0039]FIG. 23 illustrates a current range produced by a typicalcontinuous sinusoidal waveform from the electrosurgical generator; and

[0040]FIG. 24 illustrates a burst mode output of an electrosurgicalgenerator showing discreet bursts of energy with increased current.

DETAILED DESCRIPTION OF THE INVENTION

[0041] The present invention is directed to an electrosurgicalinstrument for heating a lumen or a cavity within a patient. Inparticular, the present invention is directed to a bipolarelectrosurgical instrument for the treatment of Barrett's Esophagus. Abipolar electrosurgical instrument according to one embodiment of thepresent invention uses a plurality of RF balloon electrodes to heat aninner lining or layer of the esophagus to destroy diseased tissue, andto stimulate the regrowth of a new healthy inner lining. The embodimentillustrated is minimally invasive and requires the placement of theexpandable RF balloon electrodes into contact with the inner lining ofthe esophagus for the application of RF electrical energy. Oneembodiment of a bipolar electrosurgical instrument 60 is shown in FIGS.1-6 and FIGS. 9-11. Methods of using such a bipolar electrosurgicalinstrument according to the present invention are illustrated generallyshown FIGS. 13-17

[0042] As illustrated in FIG. 1, bipolar electrosurgical instrument 60has a pair of expandable electrodes for placement within an inner liningof a lumen or cavity of a patient. Unlike monopolar electrosurgicalballoon instruments, bipolar electrosurgical instruments do not havereturn electrodes placed on the exterior of the patient. The bipolarelectrosurgical instrument 60 has two distinct elongated members, afirst pole member 70 and a second pole member 90, each member having aballoon electrode near the distal end. The first pole member 70 has aballoon electrode 70 a at the distal end of a flexible elongated tube 71and the second pole member 90 has a return balloon electrode 90 a at adistal end of a flexible return sleeve 92. In one embodiment of thepresent invention, the return balloon electrode 90 a has at least twicethe surface area of the balloon electrode 70 a to confine thetissue-heating effects to tissue directly adjacent to balloon electrode70 a.

[0043] The second pole member 90 has a return sleeve body 100 at theproximal end of the flexible return sleeve 92 and the return balloonelectrode 90 a at the distal end. The flexible elongated tube 71 of thefirst pole member 70 is connected to the return sleeve body 100 of thesecond pole member 90 by a flexible coupling tube 104 for the passage ofa conductive fluid 74, and a first pole wire 105 for the conduction ofelectrical energy.

[0044] Flexible return sleeve 92 and flexible elongated tube 71 havehollow passageways for the passage of conductive fluid 74 to the balloonelectrodes (FIGS. 5 and 17), and electrical wiring or conductors toconduct RF electrical energy to the balloon electrodes. The electricalwiring and hollow passageways from the elongated members are broughttogether at the return sleeve body 100. A balloon electrode fluid line103 and a return balloon fluid line 102 are attached to the returnsleeve body 100 for the passage of conductive fluid 74 to the balloonelectrode 70 a and to the return balloon electrode 90 a, respectively,for the expansion of the balloon electrodes. The proximal ends of theballoon electrode fluid line 103 and the return balloon fluid line 102are connected to a pressurized fluid source 51 for the expansion of theballoon electrodes. Bipolar electrosurgical instrument 60 has aconnector cable 67 and an electrical connector 66 (FIG. 1) that areelectrically connected to a RF generator 50 (FIG. 13). The RF (RadioFrequency) electrosurgical generator 50 provides RF energy to theelectrosurgical instrument, preferably at a frequency between the rangeof 0.5 MHz to 20 MHz. The connector wire 67 is electrically connected tothe balloon electrode 70 a by a first pole wire 105 and to the returnballoon electrode 90 a by first pole conductor 94.

[0045] As illustrated in FIGS. 2 and 3, the bipolar electrosurgicalinstrument 60 is adapted for use with an endoscope 40. The endoscope 40is commercially available and has a proximal endoscope handle 41 for thesurgeon to grasp, a bendable or articulatable endoscope shaft 42extending distally from the endoscope handle 41 for insertion into apatient, and a hollow operative channel 43 within the endoscope shaft42. The hollow operative channel 43 extends from an endoscope accessport 45 to a distal end of the endoscope shaft 42 for the placement ofsurgical instruments within. The distal end of the endoscope shaft 42has a viewing optics 44 located therein providing the surgeon with aview from the distal end of the endoscope 40. It is recommended that thebipolar electrosurgical instrument 60 be attached to the endoscope 40prior to the placement of the endoscope into a patient 33 (FIG. 13).

[0046] The second pole member 90 of the bipolar electrosurgicalinstrument 60 slideably mounts on the exterior of the endoscope shaft 42by passing the distal end of the endoscopic shaft 42 into the hollowlumen 99 of the flexible return sleeve 92. An attachment knob 101 islocated on the return sleeve body 100 and rotation of the attachmentknob 101 locks the second pole member 90 to the endoscope shaft 42. Theattachment knob 101 is attached to a threaded shaft 101 a (FIG. 3) thatrotates in a threaded hole 100 a in the return sleeve body 100. Rotationof the knob 101 moves the threaded shaft 101 a inward into the bore 106of the return sleeve body 100 and into contact with the exterior of theendoscope shaft 42. This contact locks the second pole member 90 to theendoscope shaft 42.

[0047] The balloon electrode 70 a at the distal end of flexibleelongated tube 71 is placed into the endoscope access port 45 andemerges from the distal end of the operative channel 43 (FIG. 2) of theendoscope shaft 42 to expose the balloon electrode 70 a. It is importantto note that the balloon electrode 70 a is spaced a distance “L” fromthe return balloon electrode 90 a wherein “L” is at least twice thelongitudinal length of the balloon electrode 70 a. The balloonelectrodes 70 a and 90 a can be spaced apart the distance “L” prior toinsertion into the patient or while in the patient. This spreads thecurrent density apart.

[0048] The distal balloon electrode 70 a and the flexible elongated tube71 are shown in greater detail in FIGS. 4, 5, 6, and 9. Both the balloonelectrode 70 a and the flexible elongated tube 71 are filled with aconductive fluid 74 (FIG. 5) for the conduction of RF energy to tissuein contact with the balloon electrode 70 a. To ensure contact betweenthe balloon electrode 70 a and the diseased inner lining of theesophagus, the balloon electrode 70 a has an expandable sleeve 75 thatis expanded by pressurizing the conductive fluid 74.

[0049] The elements of the balloon electrode 70 a and the flexibleelongated tube 71 are illustrated in FIGS. 4, 5, and 6. The balloonelectrode 70 a of FIG. 4 has the expandable sleeve 75 extending from thedistal end of the flexible elongated tube 71 and an end guide cap 80attached to the distal end of the expandable sleeve 75. Ideally, theexpandable sleeve 75 is formed from silicone, polyurethane,polyethylene, polypropylene, Teflon, or any one of a number of elasticor semi-elastic engineering materials with low electrical conductivity(e.g. acts as an electrical isolator) and heat resistant properties. Theflexible elongated tube 71 is formed from a flexible engineeringthermoplastic such as nylon, polyurethane, polyethylene, polypropylene,Teflon and the like. The expandable sleeve 75 has a lower electricalpermeativity than the flexible elongated tube 71. This can beaccomplished by a judicious use of materials or, if the same material isused for both elements, a thinner cross section is used with theexpandable sleeve 75. The expandable sleeve 75 is hermetically attachedto the end guide cap by a distal retaining sleeve 77 and to the flexibleelongated tube 71 by a proximal retaining sleeve 76. Whereas theillustrated embodiment uses a heat shrinkable tubing for the distalretaining sleeve 77 and the proximal retaining sleeve 76, other hermeticattachment methods are available such as glue, heat staking, crimpfittings, and the like. The flexible elongated tube 71, the expandablesleeve 75, and the end guide cap 80, of the illustrated embodiment arefilled with a conductive fluid 74 (Figures) such as saline and the likefor the conduction of electricity from a first pole electrode 72 intothe expandable sleeve 75.

[0050]FIG. 5 shows a cross section view of the balloon electrode 70 aand the elements within flexible elongated tube 71 and FIG. 6 shows anexploded view of these elements. A hollow spacer tube 78 is fixed (notshown) longitudinally within the flexible elongated tube 71. A firstpole electrode 72 is fixedly attached about the spacer tube 78 and islocated within and proximally recessed from both the distal end of theflexible elongated tube 71 and the expandable sleeve 75. The first poleelectrode 72 is formed from wire braid and is electrically connected tothe electrical connector 66 and the RF electrosurgical generator 50(FIG. 13).

[0051] A non-conductive semi-rigid support 73 extends from the flexiblespacer tube 78 and into the end guide cap 80. The semi-rigid support 73of the illustrated embodiment is a non-conductive spring formed from thedistal end of the spacer tube 78. It should be obvious to one skilled inthe art that the semi-rigid support 73 can be formed as a separate piecedistinct from spacer tube 78. The end guide cap 80 has an annular innerring 81 for the reception of the semi-rigid support 73. The inner ring81 is hermetically attached to a rigid or semi-rigid guide cap plug 82and the expandable sleeve 75 by the distal retaining sleeve 77.

[0052] The guide cap plug 82 and the distal retaining sleeve 77 of theend guide cap 80, are rounded to provide an atraumatic tissue contactsurface upon the distal end of the balloon electrode 70 a. Thenon-conductive semi-rigid support 73 attaches the end guide cap 80 tothe flexible elongated tube 71 and deflects to reduce possible tissueimpact trauma. Additionally, the non-conductive semi-rigid support 73bends the balloon electrode to the shape of the lumen or cavity andaround corners when maneuvering a torturous lumen or passage.

[0053]FIG. 7 is a cross sectional view of the balloon electrode 70 ashowing the expandable sleeve 75 in the expanded position. Pressurizingthe conductive fluid 74 with a pressurizable fluid source 51 (FIGS. 1and 2) forces additional conductive fluid 74 into the flexible elongatedtube 71 and the hollow spacer tube 78 and expands the expandable sleeve75. The pressurizable fluid source 51 can be a pressurized saline linesuch as found in an operating room, a conductive fluid 74 filledhypodermic, a conductive fluid 74 filled pressure squeeze bulb, or anyother apparatus or method of delivering additional conductive fluid 74to the expandable sleeve 75.

[0054]FIGS. 8 and 9 illustrate an alternate embodiment of the balloonelectrode 70 a shown in FIG. 7. In FIG. 8, the recessed first poleelectrode 72 (FIG. 7) is replaced with an isolated first pole electrode85 within the non-conductive semi-rigid support 73. In the illustratedembodiment of the alternate design the isolated first pole electrode 85is a conductive material attached to an inner surface 73 a of thesemi-rigid support 73. The such isolated first pole electrode 85 can bea layer of conductive plating or a thin layer of metal such as silver,copper, aluminum, or any other conductive material adhered to or placedwithin the inner surface 73 a of the semi-rigid support 73. An insulatedelectrode wire 86 electrically connects the isolated first poleelectrode 85 to the first pole wire 105 (FIG. 2). During operation, thesemi-rigid support 73 acts as a protective isolator for isolated firstpole electrode 85 and prevents possible damage to the expandable sleeve75. It is also obvious to one skilled in the art to replace theconductive plating or layer of metal of the isolated first poleelectrode 85 with a metallic form such as a conductive spring of properlength and diameter to lie within the semi-rigid support 73.

[0055]FIG. 9 is a section view of the inflated balloon electrode 70 a ofthe alternate embodiment wherein the bipolar electrosurgical instrument60 is energized. It is important to note that the isolated first poleelectrode 85 is spaced away from the proximal and distal ends of theexpandable sleeve 75 and is centered in the areas of maximum salinevolume. This is done to confine the current flow to the areas adjacentto the areas of maximum saline volume and to eliminate possible hotspots in the balloon electrode 70 a. A current flow pattern 87 is shownemanating from the spiral opening 73 b of the semi-rigid support 73. Asshown in the cross section of FIG. 9, the current flow pattern 87 isemitted in the shape of a truncated cone through the spiral opening 73 band flows from the inner surface 73 a outwards through the spiralopening 73 b. The spiral opening 73 b in the non-conducting semi-rigidsupport 73 bleeds off the high energy density created within thesemi-rigid support member 73. Whereas the illustrated embodiment has thespiral opening 73 b in the semi-rigid support 73, it is within the scopeof the present invention to use a number of openings of sufficient sizeto bleed off the high energy density in the manner described above.

[0056] The elements of the expandable return balloon electrode 90 a areshown in FIGS. 10, 11, and 17. The return balloon electrode 90 a has anouter expandable return balloon sleeve 95 that forms a proximal and adistal hermetic seal with the flexible return sleeve 92, and a secondpole electrode 91 within. It is important to note that the expandablereturn balloon sleeve 95 of the expandable return balloon electrode 90 ahas at least twice the surface area of the expandable sleeve 75 of theballoon electrode 70 a. Second pole electrode 91 is electricallyisolated from contact with the patient 33 by the expandable returnballoon sleeve 95 and the flexible return sleeve 92. The expandablereturn balloon sleeve 95 can be formed from the same materials as theexpandable sleeve 75 described above and has a lower electricalpermeativity than the flexible elongated tube 71 and the flexible returnsleeve 92. A fluid passage 93 and a first pole conductor 94 runlongitudinally within the flexible return sleeve 92 which is formed froma flexible engineering thermoplastic such as nylon, polyurethane,polyethylene, or the like (FIG. 17). The fluid passage 93 connects thereturn balloon electrode 90 a with the return sleeve body 100 and thereturn balloon fluid line 102 for the passage of pressurized conductivefluid 74 to inflate the return balloon electrode 90 a (dashed lines inFIG. 11). The first pole conductor 94 is electrically connected to theelectrical connector 66 by the second pole electrode 91 and theconnector cable 67 for the passage of RF energy. A distal sleeve 98 anda proximal sleeve 97 are used to attach and hermetically seal theexpandable return balloon sleeve 95 to the flexible return sleeve 92.Like the balloon sleeve attachment methods described above, theexpandable return balloon sleeve 95 is attached using heat shrinkabletubing (for the distal retaining sleeve 77 and the proximal retainingsleeve 76). Other hermetic attachment methods are available such asglue, heat staking, crimp fittings and the like.

[0057]FIG. 12 is a cross section view of the lower esophagus 25 and theupper portion of the stomach 27 showing the diseased inner lining of theesophagus 25, henceforth referred to as Barrett's Esophagus. Barrett'sEsophagus is identified by a change in the mucosal inner lining 29 ofthe esophagus 25. The chronic exposure of the inner lining 29 to gastricsecretions that leak past a defective lower esophageal sphincter 28changes the healthy epithelium of the inner lining 29 to a diseasedcolumnar epithelium 30. A possibly pre-cancerous squamous epithelium 31condition of the inner lining 29 is also shown. A circular esophagealmuscle 32 lies beneath the inner lining 29 of the esophagus 25.

[0058]FIG. 13 is a section view of the patient 33, showing the endoscopeshaft 42 of the endoscope 40 insertion into the mouth 26 and esophagusof a patient 33. The bipolar electrosurgical instrument 60 is attachedto the endoscope and the balloon electrode 70 a is extending distallyfrom the operative channel 43 (FIG. 2) of the endoscope 40. Theexpandable sleeve 75 of the balloon electrode 70 a is expanded intocontact with the inner lining 29 of the esophagus 25 by the connectionof the balloon electrode fluid line 103 to the pressurizable fluidsource 51. The endoscope shaft 42 is curved to place the un-expandedreturn balloon electrode 90 a into contact with the inner lining 29 ofthe esophagus 25 to provide the return path for the electrical energy.The return balloon electrode 90 a is larger in diameter than the balloonelectrode 70 a and need not be expanded if enough surface area of theexpandable return balloon sleeve 95 is in contact with tissue. Theelectrical connector 66 of the bipolar electrosurgical instrument 60 isconnected to the RF electrosurgical generator 50.

[0059]FIG. 14 shows the placement of the balloon electrode 70 a at thesite of the columnar epithelium 30 prior to the application of RF energyto the diseased area of the inner inning 29. The balloon electrode 70 ais visible in a viewing angle 46 of the viewing optics 44 and thesurgeon has visually maneuvered the balloon electrode 70 a into contactwith the columnar epithelium 30. Ideally, this maneuvering is done priorto the expansion of the expandable sleeve 75. The expandable sleeve 75is shown expanded to contact the diseased columnar epithelium 30.

[0060]FIGS. 15 and 16 shows the placement of the return balloonelectrode 90 a of the bipolar electrosurgical instrument 60 just priorto the application of RF energy. Both the balloon electrode 70 a and thereturn balloon electrode 90 a are expanded and in contact with tissue.In FIG. 16, the balloon electrode 70 a is contacting the columnarepithelium 30 found on the inner lining of the esophagus 25 and thereturn balloon electrode 90 a is moving from the initial position shownin FIG. 15 to the final position shown in FIG. 16. This movement spacesthe return balloon electrode 90 a the previously described distance “L”from the balloon electrode 70 a and the effects of this action will nowbe described.

[0061] There is a threshold of energy density in tissue that must be metbefore tissue effects can occur. When the energy density is below thethreshold, the tissue is unaffected by the application of energy. Whenthe energy density rises above the threshold, the tissue is affected bythe energy and begins to heat or cook. With the illustrated bipolarelectrosurgical surgical instrument 60, the energy density is spreadbetween the two balloon electrodes 70 a and 90 a, somewhat analogous tomagnetic lines of force between two magnets. It is desired toconcentrate the energy density at the distal balloon electrode 70 a anddilute the energy density at the larger proximal return balloonelectrode 90 a.

[0062] This is accomplished in two ways, first, the return balloonelectrode 90 a is at least twice as large as the balloon electrode 70 aand second, the return balloon electrode 90 a must be spaced at leastthe distance “L” (described above) from the distal balloon electrode 70a. In bipolar balloon energy devices, energy density is distributedevenly per unit of surface area on each balloon and likewise withinadjacent surrounding tissue. Since the return balloon electrode 90 a hastwice the surface area of the balloon electrode 70 a, the energy densityin the tissue directly adjacent to return balloon electrode 90 a is halfof that found near the balloon electrode 70 a and below the threshold ofenergy density necessary to heat tissue. The energy density in tissuedirectly adjacent to the smaller balloon electrode 70 a is twice that ofthe return balloon electrode 90 a and over the energy density thresholdto heat tissue.

[0063] Electrical energy seeks the shortest path, and separating theballoon electrodes spreads the energy densities found in tissue locateddirectly between the two balloon electrodes to below the energy densitythreshold. When the path between the balloon electrodes is short, theenergy tries to flow from the closest surface to the closest surface andthe energy density is concentrated or funneled into the tissue betweenthe balloon electrodes. This heats tissue directly in the path betweenthe two balloon electrodes. Separating the balloon electrodes has theeffect of spreading the current density out in the tissue directlybetween the balloon electrodes and concentrating the energy density inthe tissue adjacent to the balloon electrodes. This ensures that thesmallest of the two balloon electrodes, distal balloon electrode 70 a,has the highest current density surrounding it to confine tissue-heatingeffects to tissue directly adjacent to balloon electrode 70 a. If thetwo balloon electrodes are spaced apart at a distance less than “L”,then the surgeon runs the risk of shifting the highest current densityto the tissue between the balloon electrodes and moving the tissueheating effects away from the smaller balloon electrode 70 a.

[0064] The balloon electrode 70 a and the return balloon electrode 90 aare shown in the expanded condition by the connection of the first polefluid line (FIG. 9 and 10) and the flexible elongated tube 71 to thepressurizable fluid source 51 (FIG. 10). Electrical energy is applied tothe second pole electrode 91 and the first pole electrode 72 to gentlyheat (not shown) the inner lining 29 surrounding the balloon electrode70 a by capacitive coupling. After the application of electrical energyto heat the tissue, the balloon electrode 70 a and the return balloonelectrode 90 a are deflated and the bipolar electrosurgical instrumentis removed from the patient (not shown).

[0065]FIGS. 18 and 19 shows alternate embodiments of the balloonelectrode 70 a of the bipolar electrosurgical instrument 60 wherein theexpandable sleeve 75 is made from a translucent or transparent materialsuch as silicone, polyurethane, polyethylene, polypropylene, Teflon, orthe like. The translucent expandable sleeve 111 (FIG. 18) providesincreased visibility of the surgical site during placement of theballoon electrode 70 a by enabling the surgeon to view through thetranslucent expandable sleeve 111. Additionally, tissue-heating effectscan be monitored through the translucent expandable sleeve 111. As shownin FIG. 19, a transparent expandable sleeve 110 would offer even greatervisibility over the translucent expandable sleeve 111 and could beformed from the same materials listed above.

[0066]FIG. 20 is a cross sectional view along the longitudinal axis ofan alternate embodiment of a bipolar dual balloon end effector 120.Instead of a single balloon electrode 70 a at the distal end of theflexible elongated tube 71, the dual balloon end effector 120 of thealternate embodiment has a pair of expandable electrodes side by side ina longitudinal orientation. FIG. 20 is a cross sectional view takenperpendicular to the longitudinal axis of the dual balloon end effector120 and shows a cross section of a first pole balloon electrode 125 onthe left and a cross section of a second pole balloon electrode 130 onthe right. First pole balloon electrode 125 and second pole balloonelectrode 130 are separated by an isolator wall 121 to prevent contactbetween the balloon electrodes and are backed by a proximal end plate122. Each balloon electrode 125, 130 is identical to and a mirror imageof the other. The first pole balloon electrode 125 has a first poleballoon sleeve 126 that is expandable by the addition of conductivefluid 74 from the pressurizable fluid source 51. The conductive fluid 74is conducted into the first pole balloon sleeve 126 by a first polefluid passage 127 that extends through the flexible elongated tube 71that is connected to the pressurizable fluid source 51. A first dualelectrode 128 is recessed into the proximal end plate 122 for thedelivery of electrical energy to the first pole balloon electrode. Likethe mirror image first pole electrode 125 described above, the secondpole electrode 130 has a second pole balloon sleeve 131, a second polefluid passage 132, and a second dual electrode 133. The application ofRF energy to bipolar dual balloon end effector 120 heats the adjacenttissue by capacitive coupling much in the manner described above.Heating effects from this design are more pronounced along a horizontalplane that runs through the first dual electrode 128 and second poleballoon fluid passage 132. Less heating is found along a vertical planeestablished by the isolator wall 121. This type of end effector providesthe surgeon with localized and opposite lobes of heating which can leavehealthy tissue between the lobes unscathed.

[0067]FIG. 25 shows yet another alternative embodiment of an alternatebipolar electrosurgical instrument 140 wherein the alternate embodimenthas a multiplicity of expandable electrodes spaced longitudinally alongthe longitudinal axis of the alternate bipolar electrosurgicalinstrument 140. In FIG. 21, three balloon electrodes are shown, distalballoon electrode 70 a, return balloon electrode 90 a, and an alternateballoon electrode 141 located proximally from return balloon electrode90 a. A switching network 142 is provided to switch the application ofbipolar RF energy from the distal balloon electrode 70 a and the returnballoon electrode 90 a to the alternate balloon electrode 141 and thereturn balloon electrode 90 a. This switching effectively enables thesurgeon to move the application of RF energy from the distal mostballoon electrode 70 a to the proximal most alternate balloon electrode141 without moving the bipolar electrosurgical instrument 120. It isimportant to note that the central return balloon electrode 90 a is atleast twice the size of the proximal alternate balloon electrode 141 andthe distal balloon electrode 70 a. Also of note is the distance “L”between the pair of selected balloon electrodes is at least twice thelongitudinal length of the return balloon electrode 90 a or alternateballoon electrode 141. This ensures that the smaller of the two balloonelectrodes selected has the highest current density surrounding it toconfine tissue-heating effects to tissue directly adjacent to thesmaller balloon electrode.

[0068] In yet another embodiment of the invention and as shown in FIGS.22-24 the output of the RF electrosurgical generator 50 to the bipolarballoon electrodes is altered from a continuous sinusoidal output 150(FIG. 22) to a pulsed “burst” mode 155 (FIG. 24). The output of a RFgenerator 51 in cautery mode is a continuous sinusoidal output 150 of afrequency dependent on the generator and at a typical current of 0.75 to1 amps (FIG. 23). In “burst” mode 155, the sinusoidal output 150 of thegenerator is retained but the application of the waveform to tissue isbroken up into discreet “bursts” or pulses of energy separated byperiods of no energy application. The bursts of energy 156 are appliedfor approximately 2-100 milliseconds, and most preferably around 10milliseconds. The bursts of energy 156 are applied at a rate of 2 to 500Hz and most preferably between 50-100 Hz. The current 151 applied duringthe pulse is increased to between 1.5 to 5 amps and most preferably at 2amps. Providing bursts of increased current 151 results in the averagepower being kept between 2-100 watts and most preferably below 20 watts.By providing short bursts of energy 156 of higher current 151, the netenergy applied to the tissue is less or equal to the energy applied bythe steady sinusoidal output 150 of an unmodified RF generator.

[0069] Testing has shown that the application of pulsed RF energy in themanner described above results in decreased internal heating of theconductive fluid within the balloon electrode, and limits the depth ofpenetration of the RF energy into the wall of the lumen. Additionally,tissue effects produced by the bursts of energy 156 are visuallydifferent from tissue treated with a continuous output sinusoidalwaveform 150, and have more of a “sunburned tissue” effect than the moretypical “cooked tissue” effect produced by the application of continuoussinusoidal RF energy.

[0070] While preferred embodiments of the present invention have beenshown and described herein, it will be obvious to those skilled in theart that such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. Accordingly, it isintended that the invention be limited only by the spirit and scope ofthe appended claims.

What is claimed is:
 1. A bipolar electrosurgical instrument for heatingthe inner lining of a lumen or cavity within a patient, saidelectrosurgical instrument comprising: a flexible elongated tube havinga proximal and a distal end; a first balloon electrode attached to saiddistal end of said flexible elongated tube wherein said first balloonelectrode comprises: a first expandable sleeve formed from anelectrically insulating material; a first electrically conductive fluidin said expandable sleeve a first electrode in electrical contact withsaid first electrically conductive fluid; a return balloon electrodespaced proximally from said first balloon electrode, wherein said returnballoon electrode comprises: a second expandable sleeve formed from anelectrically insulating material; a second electrically conductive fluiddisposed within said second expandable sleeve; and a return electrode inelectrical contact with said second electrically conductive fluid.
 2. Abipolar electrosurgical instrument according to claim 1 , wherein saidfirst expandable sleeve is expanded such that a portion of said firstexpandable sleeve is adapted to be in contact with a first portion ofsaid inner lining and a portion of said second expandable sleeve isadapted to be in contact with a second portion of said inner lining,wherein said second portion of said inner lining is at least twice aslarge in area as said first portion of said inner lining.
 3. A bipolarelectrosurgical instrument according to claim 2 , wherein said secondexpandable sleeve has a length L and wherein a proximal end of saidfirst expandable sleeve is positioned a distance of at least 2L from adistal end of said second expandable sleeve.
 4. A bipolarelectrosurgical instrument according to claim 2 wherein saidelectrically insulating material has a lower electrical permeativitythan said flexible elongated tube.
 5. A bipolar electrosurgicalinstrument according to claim 1 further comprising a non-conductingsemi-rigid support extending distally within said expandable sleeve froma distal end of said flexible elongated tube.
 6. A bipolarelectrosurgical instrument according to claim 5 wherein saidnon-conducting semi-rigid support is a spring.
 7. A bipolarelectrosurgical instrument according to claim 5 further comprising anend guide cap attached to a distal end of said expandable sleeve and adistal end of said non-conducting semi-rigid support, said guide cap forguiding said electrosurgical instrument into said lumen or cavity.
 8. Abipolar electrosurgical instrument according to claim 1 wherein saidfirst electrode is located within and recessed proximally from saiddistal end of said flexible elongated tube.
 9. A bipolar electrosurgicalinstrument according to claim 8 wherein said first electrode is abraided metallic wire.
 10. A bipolar electrosurgical instrumentaccording to claim 1 wherein said first expandable sleeve includes aconductive coating on an inner surface thereof.
 11. A bipolarelectrosurgical instrument according to claim 1 wherein the electricalenergy applied to said first balloon electrode is radio frequency energyat a frequency of 0.5 MHz. to 20 MHz.